Sinister Seduction: Pitcherplants and Their Prey

Svelte and stately or squat and trollish, pitcherplants beguile not only bugs but humans. Their carnivorous habit fascinates, especially since they have no moving traps. More than 100 species of pitcherplants occur on four continents – Asia, Australia and the Americas. Each species has tubular leaf traps that collect rainwater and secrete digestive enzymes. They lure small animals to these death-pools with elusive sweet nectar and striking colors. However, pitcherplants are not all close relatives; this prey-luring mechanism has evolved many times. Pitcherplant species occur in four plant families, Bromeliaceae, Cephalotaceae, Nepenthaceae and Sarraceniaceae, each of which is in a different taxonomic order of flowering plants.

Georgia’s pitcherplants are all in the genus Sarracenia, which is endemic to North America. In just this one genus, there are distinct differences in carnivory. Let’s take a look at three of Georgia’s seven Sarracenia species: S. flava, S. minor and S. purpurea.

Sarracenia flava, aka trumpet pitcherplant or yellow flytrap, is a grand species with bright yellow-green pitchers that can be up to a meter tall. S. flava is one of Georgia’s more common pitcherplants, and its range is the southeastern Coastal Plain from Alabama and the Florida panhandle up through the Carolinas to Virginia. Nectar production is concentrated near the lip of the pitcher, with the heaviest concentrations just above the opening beneath the lid.

Photo Credit: Laura Hall

Going for the gold, insects navigate to this precipitous overhang. But there’s no good grip here: A waxy surface with downward pointed hairs in the pitcher below makes any misstep a disaster as the insect slips into the trap and the digestive liquid within.

Photo Credit: Stewart McPherson

Sarracenia minor is a conniving bug killer known as the hooded pitcherplant, both for its street cred as well as the nearly closed, dome-shaped lids on its pitchers. This species offers up its nectar – pure bug bling – at the entrance to its pitchers, which are shaded by the hood. Sparkling at the back of the hood are translucent patches where chlorophyll is lacking in the leaf. Illuminated in sunlight, these “windows” draw insects that explore the entrance to the trap, and, misled by the light, fly toward this false escape route. The unwitting victims collide with the back of the pitcher and fall straight down to their demise.

Like S. flava, S. minor is one of Georgia’s more common Coastal Plain pitchers, more tolerant of drought and soil disturbance than most of its congeners. Its distribution is from Florida to the Carolinas.

Photo Credit: Christa Frangiamore

Sarracenia purpurea, the purple pitcherplant, contrasts strongly in form with other Georgia pitcherplant species. Its stocky pitchers are nearly supine, and their wide-open lids offer no protection from the diluting effects of rainwater on their digestive enzymes. S. purpurea relies less on enzymes than other pitcherplant species, and its enzyme production declines as the leaves age.

Photo Credit: Brad Wilson

Which brings us to a new frontier: Pitcherplants do not operate alone in their flesh-consuming universe. Digestion in all Sarracenia is aided by a microcosm of bacteria, unique in its species composition to the realm within their pitchers.

Sarracenia purpurea has even greater complexity. Three species of insect larvae inhabit the food web enclosed in its pitchers: larvae of a fly, a midge and a mosquito. Each is associated only with the purple pitcherplant. They specialize in feeding on carcasses of drowned insects. The midge and the fly larvae shred prey into more quickly decomposing parts, while the mosquito larvae filter feed on smaller prey remnants suspended in the milieu. All of the food web inhabitants assist in breaking down prey into the nutrients the pitcherplants need.

S. purpurea has several varieties. The species broadly occurs in the southeastern U.S. north into Canada, growing widely across the boreal regions of North America. In Georgia, however, it is incredibly rare. Here, the mountain purple pitcherplant occurs naturally in only one location and the Coastal Plain purple pitcherplant occurs only in two counties.

All of Georgia’s Sarracenia species are threatened in the wild due to pressures from human population growth. Particularly problematic are disturbances that disrupt the seeping water flows in their fragile wetland habitats, or that allow more aggressive plants to compete for sun and water. Therefore, wetland drainage, intensive timber practices and fire suppression are primary threats to pitcherplant species. In Georgia, Sarracenia conservation is a primary project of the Georgia Plant Conservation Alliance, whose partners work on many fronts – ecological, horticultural and educational – to preserve pitcherplant populations and their habitats.

Nonetheless, you can enjoy and showcase Sarracenia at home, as they are relatively easy to maintain in cultivation. If you would like to add Sarracenia to your garden, take utmost care to purchase plants grown ethically from appropriately sourced seed. It is critical that Sarracenia are never collected from the wild. They are a delight to observe throughout the seasons. In the spring, nascent pitchers emerge in brilliant colors. In late summer and autumn, the nectar can be so strong insects coming to your wildflowers will inevitably be diverted to the deadly pitchers. In winter, slice open their senescent leaves to observe the animal remains within. You may even find a dragonfly or an unfortunate anole!

In endless ways, Sarracenia are an incredible part of Georgia’s natural heritage.

For More

Pitcherplants of the Americas, by Stewart McPherson (The McDonald & Woodward Publishing Co.)

Carnivorous Plants of the United States and Canada, by Donald E. Schnell (John F. Blair, publisher)